Archive for January, 2021

Flat Dirty Ridge to become highly amplified next week as Polar Vortex desends southward……Our Long Range Dry Outlook is not set in stone!!

The Strato Warming is in process.   Temperatures have risen strongly over the stratosphere above the arctic,  increasing high pressure below in the troposphere. It will be interesting to see what the long range models will do with the Polar Vortex’s over the coming weeks. Over the western hemisiphier, the global models at 500MB show the PV strongly developing near the Hudson Bay Area by mid January. This really amplifies the planetary wave pattern with Trof-Ridge Trof pattern between the dateline and the Eastern US.   This highly Amped ridge is whats in store for the far west next week with very warm temps for California, especially the southern half, Wednesday through Friday and possibly Saturday. After that, all hell may break loose over the northern hemisiphier the following week….

At the moment, the Polar Vortex has been broken into a few parts as the displacing polar positive height anomaly develops. Week (2) of todays 12z Euro shows several more PVs breaking off forming smaller ones all over the northern mid latitudes.  Currently, The major PV is deep over far Eastern Asia with a smaller one over Western Europe. The Sudden Strato warming has really done its job, with 500MB heights anomaliously high over much of the Polar Region. The stage is set for some really “wild weather”, during the latter part of January. However, no one really knows how it will affect the west coast yet. Again, next week, the Euro has the PV setting up near the Hudson Bay area with a highly amped ridge off the west coast. (Cold east/warm west) Over-time, there looks to be retrogression in the positive height anomaly and that’s where our pattern can really change.   I would NOT! put much faith in the week two models yet, untill we see how this change affects the northern hemisiphieric pattern as our west coast weather evolves.

PS plan your bike rides Wednesday through Friday….:-)

 

The Dweeber……………….:-)

Global forecast models have back peddeled on precipitation prospects for the month of January…..Occasional fast moving systems likely to bring only light amounts for Mono County

Tuesday Jan 5th;

Central and Eastern Sierra to remain dry another 2 weeks…..

Although there are a few more fast moving short waves that will pass through mainly Northern CA the next 7 days, none are expected to bring any signifacant precipitation to the Eastern Sierra. Last nights wind storm brought 3 to 4 inches of snow to Mammoth Mt and only an inch or so to the town, while areas east were for the most part dry.   The next upstream system will follow a storm track familuar to us this Winter, as a weakening weather front drags through Southern Mono County Friday AM. The final in the series of fronts will move through Monday with little more than clouds and breeze to contend with.

If you think that this winter and fall are drier than normal, you are 100% correct.  However, there have been several dry stretches here in the Eastern Sierra histrorically. Back in the Fall, I touted that there would be a dry bias to this years winter.  This years Cold ENSO, “a moderate La Nina” is proving to be exceptionally dry one in the record books.  We can only hope for a wet February and March to help us out…

Pattern;  looking at the ECMWF ENS 7 day 500MB Height Anomalies, there is blocking from Hudson Bay east to just south of Iceland. The westerlies are strong through this countrys deep south and south east, giving many areas like the Carolinas rain and snow. The main governing anomaly for the west coast is a ridge in the mean. This is why we are not getting signifacant storms this far south. What transpires by the 10th of January is a block setting up near Greenland. This eventually will Dam Up the cold air over East Central Canada which enhances the -NAO teleconnection. Unfourtunetly, the upstream effect is a strengthing +PNA and that’s what get us into trouble. Strong height rises are expected to take place during the 2nd half of next week that will block most if not all storms from the west coast, including Washington State.

The big question is, where will the Mega Ridge set up?  If it sets up along the west coast, “high temperature records” may be in jepordy in parts of CA..  If it sets up a bit more to the west, we may get some inslide sliders.   That’s a “chilly pattern” for Eastern CA. No matter what, it is a bone dry pattern for the Eastern Sierra next week…..  La Nina is still preventing MJO from remaining strong enough through the Central Pacific to modulate the westerlies in a positive way.

 

Highs in Mammoth are expected in the 40s with lows in the teens and Twenties.  The remainder of this week looks pretty uneventful with the exception of Friday which will be breezy with some snowshowers…

 

Dr Howard and the Dweebs………………:-)

 

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Although the Strat warming now in process has created strong high pressure in many areas of the Arctic, the over riding effects of a cold ENSO are proving to be more than enough to keep our weather drier than normal here in Southern Mono County.   Checking the key teleconnections from the GFS ENS and ECMWF ENS, although they both tout the -AO with a positive height anomaly over parts of the Arctic, the over riding factor is the +PNA, the pacific north american cir for the Eastern Pacific and far west is in its positive phase.  This keeps the upper jet for the most part, far enough north for just modest amounts of moisture from storms the next few weeks. Another factor is that the -NAO which highlights the Greenland High and Hudson Bay Low, will tend to strengthen the west coast high pressure system even further, during the second week of January into the 3rd.   (LA may experience 80s in Mid January).

All in all, the hopes of the Dweebs for some good snow producing storms have been dampened greatly by the effects of the on going dry La Nina.  The dry La Nina appears to be the over riding factor, giving all extended forecasters quite the head fake from what looked quite promissing, just a week to ten days ago. What I see now are fast moving storms that bring mainly wind, and light amounts of snowfall this week.

Currently, our sierra snowpack is running about as dry as its been historically at this time. The driest year was 2014-15. Our snow pack is running less than 30% of normal for this time of the year.

 

Forecast:

Expect two fast moving systems this week.  One today Monday and another Friday. Both will bring mainly light amounts of snowfall, (1-6 inches) with a bit more possibly, just today over the highest elevations. Any snowfall for next week will have to occur during the first half, as strong height rises next week is likley to shunt everything to our north by mid week, next week.  High temps in Mammoth will range in the upper 30s to low 40s. Lows at night in the teens and twenties.  Strong gusty winds are expected today Monday and again Friday.

 

Dr Howard and the Dweebs………………….:-)